Development of next generation cell or battery relating to the next generation vehicle and the introduction and spread of renewable energy is one of the recent attractive technologies which contribute to enhancement in the industrial competitiveness of Japan. In the fields of the next generation batteries, in addition to the efforts of further improvement of performance of lithium batteries which are presently used widely, research and development of new rechargeable cell or battery (secondary battery) or power generation cell or battery (primary battery) which takes the place of lithium batteries are now being conducted actively.
As the next generation battery which takes the place of lithium batteries, there are cells or batteries which use magnesium. Magnesium presents in the earth much larger than lithium as resources and it is superior in the view points of environmental safety.
Some technologies in relation to the batteries or cells in which magnesium or its alloy is used as negative active material are already disclosed or proposed in, for example, the following patent documents 1-3 or non-patent document 4.
The patent document 1 (Japanese Patent Kokai-Publication No. Hei 05-225978) discloses a magnesium manganese dioxide battery in which magnesium or its alloy is used as the negative active material, manganese dioxide is used as positive active material, and is used as positive active material, and magnesium perchlorate is used as primary electrolyte solution. The positive active material is so constituted that it involves activation chemical processed manganese dioxide primarily consisting of γ-crystal of barium in the amount of 0.4-6.0 weight percent.
The patent document 2 (Japanese Patent Kokai-Publication No. Hei 05-225979) also discloses a magnesium manganese dioxide battery in which magnesium or its alloy is used as the negative active material, manganese dioxide is used as positive active material, and magnesium perchlorate is used as primary electrolyte solution. In this battery, the positive active material is so constituted that it involves chemical synthesis manganese dioxide which comprises γ-crystal as main constituent, which is resulted from acid-process of manganese oxide, the manganese oxide being obtained by baking of manganese sulfate.
Further, the patent document 3 (Japanese Patent Kokai-Publication No. 2010-182435) discloses a magnesium battery which comprises a negative electrode formed of magnesium and a solution container adapted to keep therein electrolyte solution which allows elution of magnesium ion from the negative electrode. The solution container is constituted to keep therein poly-carboxylate (polyvalent carboxylate) solution as the aqueous electrolyte solution.
Furthermore, non-patent document 1 discloses an air magnesium battery which is so constituted that oxygen in the air is used as the positive active material, magnesium is used as the negative active material, and a solution of salt is used as the electrolyte solution.